L415/N08825双金属复合管热丝TIG焊工艺研究

Hot Wire TIG Welding Process of L415/N08825 Bimetallic Composite Pipe

针对L415/N08825双金属复合管,选用AWS A5.14 ERNiCrMo-3焊丝,通过改变坡口角度进行热丝TIG自动焊工艺研究,分析不同坡口角度下焊接的可操作性,焊接接头金相组织、力学性能以及晶间腐蚀性。结果表明,焊缝显微组织主要由粗大的树枝状、胞状或块状奥氏体和奥氏体之间的铁素体组成;基层热影响区组织主要为珠光体和多边形铁素体,在靠近熔合线位置,晶粒较粗大,不均匀;不同坡口角度下焊接接头力学性能、晶间腐蚀结果均满足设计规范要求,从工艺优化角度及焊接成本考虑,可以选择15°U型坡口进行复合管的现场焊接施工。

For L415/N08825 bimetallic composite pipe, AWS A5.14 ERNiCrMo-3 welding wire was selected, and the hot wire TIG automatic welding process was studied by changing the bevel angle. The operating performance, microstructure,mechanical properties and intergranular corrosion of the welded joints under different bevel angles were compared and analyzed. The results show that the microstructure of the weld metal is mainly composed of coarse dendritic, cellular or massive austenite and ferrite between the austenite. The microstructure of the heat affected zone is mainly composed of pearlite and polygonal ferrite. The grains are coarse and uneven near the fusion line. The mechanical properties and intergranular corrosion results of the welded joints under different bevel angles all meet the requirements of the designed specifications. From the point of optimizing the welding process and welding cost, 15° U-shaped groove can be selected for on-site welding construction of composite pipes.